feat: отмена скана на сервере, стабильнее scan_id, упрощённый UI

- Runner: context, POST /api/scans/{id}/cancel, частичный canceled; Start до ответа createScan

- API: scanPathID (PathUnescape), лог при 404; Postgres GetScan логирует ошибки чтения

- newScanID: суффикс 8 hex; тест обновлён

- Web UI: убраны строки scan_id/from-to; скрытое поле scanId; cancel при таймауте/новом скане

Made-with: Cursor

internal/scans/runner.go

@@ -1,7 +1,9 @@
 package scans
 
 import (
+	"context"
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"log"
 	"net"
@@ -20,8 +22,10 @@ import (
 )
 
 type Runner struct {
-	store Store
-	cfg   RunnerConfig
+	store   Store
+	cfg     RunnerConfig
+	mu      sync.Mutex
+	cancels map[string]context.CancelFunc
 }
 
 type RunnerConfig struct {
@@ -52,10 +56,64 @@ func scanProgressBlend(quickDone, fullDone, total int) int {
 }
 
 func (r *Runner) Start(job ScanJob) {
-	go r.run(job)
+	ctx, cancel := context.WithCancel(context.Background())
+	r.mu.Lock()
+	if r.cancels == nil {
+		r.cancels = make(map[string]context.CancelFunc)
+	}
+	r.cancels[job.ID] = cancel
+	r.mu.Unlock()
+
+	go func() {
+		defer func() {
+			cancel()
+			r.mu.Lock()
+			delete(r.cancels, job.ID)
+			r.mu.Unlock()
+		}()
+		r.run(ctx, job)
+	}()
 }
 
-func (r *Runner) run(job ScanJob) {
+// CancelScan отменяет активный воркер скана в этом процессе. Возвращает false, если скан не числится в памяти Runner (уже завершён или не стартовал).
+func (r *Runner) CancelScan(id string) bool {
+	r.mu.Lock()
+	c, ok := r.cancels[id]
+	r.mu.Unlock()
+	if !ok || c == nil {
+		return false
+	}
+	c()
+	return true
+}
+
+func (r *Runner) markJobCanceledFromStore(jobID string) {
+	cur, ok := r.store.GetScan(jobID)
+	if !ok {
+		return
+	}
+	switch cur.Status {
+	case "done", "failed", "canceled":
+		return
+	}
+	fin := time.Now().UTC()
+	_, _ = r.store.UpdateScan(jobID, ScanUpdate{
+		Status:     "canceled",
+		Progress:   cur.Progress,
+		Stats:      cur.Stats,
+		FinishedAt: &fin,
+	})
+}
+
+func (r *Runner) run(ctx context.Context, job ScanJob) {
+	if cur, ok := r.store.GetScan(job.ID); ok && cur.Status == "canceled" {
+		return
+	}
+	if err := ctx.Err(); err != nil && errors.Is(err, context.Canceled) {
+		r.markJobCanceledFromStore(job.ID)
+		return
+	}
+
 	started := time.Now().UTC()
 	_, _ = r.store.UpdateScan(job.ID, ScanUpdate{
 		Status:    "running",
@@ -64,6 +122,11 @@ func (r *Runner) run(job ScanJob) {
 		StartedAt: &started,
 	})
 
+	if err := ctx.Err(); err != nil && errors.Is(err, context.Canceled) {
+		r.markJobCanceledFromStore(job.ID)
+		return
+	}
+
 	ips, err := expandTargets(job.CIDRs, job.ExcludeIPs)
 	if err != nil {
 		finished := time.Now().UTC()
@@ -109,10 +172,10 @@ func (r *Runner) run(job ScanJob) {
 			Status:   "running",
 			Progress: prog,
 			Stats: ScanStats{
-				HostsTotal:           total,
-				HostsUp:              u,
-				HostsPingPhaseDone:   q,
-				HostsProcessed:       f,
+				HostsTotal:         total,
+				HostsUp:            u,
+				HostsPingPhaseDone: q,
+				HostsProcessed:     f,
 			},
 		})
 	}
@@ -178,19 +241,49 @@ func (r *Runner) run(job ScanJob) {
 		go worker()
 	}
 
-	for _, ip := range ips {
-		workCh <- ip
-	}
-	close(workCh)
+	go func() {
+		defer close(workCh)
+		for _, ip := range ips {
+			select {
+			case <-ctx.Done():
+				return
+			case workCh <- ip:
+			}
+		}
+	}()
+
 	wg.Wait()
 
 	finished := time.Now().UTC()
+	mu.Lock()
+	upFinal := up
+	full := fullDone
+	quick := quickDone
+	mu.Unlock()
+
+	if ctx.Err() != nil && errors.Is(ctx.Err(), context.Canceled) && full < total {
+		st := ScanStats{
+			HostsTotal:         total,
+			HostsUp:            upFinal,
+			HostsPingPhaseDone: quick,
+			HostsProcessed:     full,
+		}
+		prog := scanProgressBlend(quick, full, total)
+		_, _ = r.store.UpdateScan(job.ID, ScanUpdate{
+			Status:     "canceled",
+			Progress:   prog,
+			Stats:      st,
+			FinishedAt: &finished,
+		})
+		return
+	}
+
 	_, _ = r.store.UpdateScan(job.ID, ScanUpdate{
 		Status:   "done",
 		Progress: 100,
 		Stats: ScanStats{
 			HostsTotal:           total,
-			HostsUp:              up,
+			HostsUp:              upFinal,
 			HostsPingPhaseDone:   total,
 			HostsProcessed:       total,
 		},